Chemical proteomic identification of functional cysteines with atypical electrophile reactivities.

Cysteine-directed covalent ligands have emerged as a versatile category of chemical probes and drugs that leverage thiol nucleophilicity to form permanent adducts with proteins of interest. Understanding the scope of cysteines that can be targeted by covalent ligands, as well as the types of electrophiles that engage these residues, represent important challenges for fully realizing the potential of cysteine-directed chemical probe discovery. Although chemical proteomic strategies have begun to address these important questions, only a limited number of electrophilic chemotypes have been explored to date.

Selective inhibition of initiator versus executioner caspases using small peptides containing unnatural amino acids.

Caspases are fundamental to many essential biological processes, including apoptosis, differentiation, and inflammation. Unregulated caspase activity is also implicated in the development and progression of several diseases, such as cancer, neurodegenerative disorders, and sepsis. Unfortunately, it is difficult to determine exactly which caspase(s) of the 11 isoforms that humans express is responsible for specific biological functions.

Reprogramming the chemodiversity of terpenoid cyclization by remolding the active site contour of epi-isozizaene synthase.

The class I terpenoid cyclase epi-isozizaene synthase (EIZS) utilizes the universal achiral isoprenoid substrate, farnesyl diphosphate, to generate epi-isozizaene as the predominant sesquiterpene cyclization product and at least five minor sesquiterpene products, making EIZS an ideal platform for the exploration of fidelity and promiscuity in a terpenoid cyclization reaction. The hydrophobic active site contour of EIZS serves as a template that enforces a single substrate conformation, and chaperones subsequently formed carbocation intermediates through a well-defined mechanistic sequence. Here, we have used the crystal structure of EIZS as a guide to systematically remold the hydrophobic active site contour in a library of 26 site-specific mutants.